CN110186803B - Real-time testing device and testing method for molecular adsorption mechanism on natural gas hydrate surface - Google Patents

Abstract

The invention provides a real-time testing device for the molecular adsorption mechanism on the surface of natural gas hydrate, comprising a natural gas cylinder, a constant temperature tank, a computer, a data acquisition circuit, a driving circuit, a microscopic observation device and a visual high-pressure reaction kettle. The natural gas is stored in the natural gas cylinder. , the outlet of the natural gas cylinder is connected with the air inlet of the visible high pressure reaction kettle. The visible high pressure reaction kettle includes the kettle body, and the constant temperature tank is communicated with the kettle body, and the circulating medium is stored in it to reduce the temperature of the kettle body. A QCM probe is set in the body, a QCM chip is placed in the QCM probe, the QCM chip is connected to one end of the drive circuit, the other end of the drive circuit is connected to the computer, the receiving end of the data acquisition circuit is connected to the QCM chip, and the output end of the data acquisition circuit is connected to the computer , The QCM chip vibrates under the drive of the drive circuit to generate a stable vibration frequency. The data acquisition circuit collects the vibration frequency of the QCM chip in real time and transmits it to the computer. The microscopic observation device is located above the visual autoclave.

Description

Real-time testing device and testing method for molecular adsorption mechanism on natural gas hydrate surface

technical field

The invention relates to the field of natural gas hydrate, in particular to a real-time testing device and testing method for molecular adsorption mechanism on the surface of natural gas hydrate.

Background technique

Natural gas hydrate is an ice-like solid hydrate formed by methane molecules and water molecules under low temperature and high pressure conditions. At present, the research methods for the surface adsorption mechanism of natural gas hydrate at the microscopic level mainly include molecular dynamics simulation and the construction of micro-observation force devices. Among them, the micro-observation force devices mainly include atomic force microscopes and other devices for testing surface mechanics. However, this kind of test device can only partially understand the adsorption characteristics of the surface of natural gas hydrate, and cannot test the mechanical changes and surface adsorption of natural gas hydrate from formation to decomposition in real time.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a real-time test device for the molecular adsorption mechanism on the surface of natural gas hydrate, which solves the problem that the existing test device cannot test the mechanical changes and surface adsorption conditions of the molecular adsorption on the surface of natural gas hydrate in real time from formation to decomposition. The present invention also provides a real-time test method for the molecular adsorption mechanism on the surface of natural gas hydrate. The test method provided by the present invention can realize the real-time measurement of the surface adsorption mechanism of natural gas hydrate from formation to decomposition.

The invention provides a real-time testing device for the molecular adsorption mechanism on the surface of natural gas hydrate, comprising a natural gas cylinder, a constant temperature tank, a computer, a data acquisition circuit, a driving circuit, a microscopic observation device and a visual high-pressure reaction kettle. Natural gas is stored, and the gas outlet of the natural gas cylinder is communicated with the air inlet of the visible high-pressure reaction kettle. The visible high-pressure reaction kettle includes a kettle body, and the constant temperature tank is communicated with the kettle body. To reduce the temperature of the kettle body, a QCM probe is set in the kettle body, a QCM chip is placed in the QCM probe, the QCM chip is connected with one end of the drive circuit, the other end of the drive circuit is connected with the computer, the data acquisition The receiving end of the circuit is connected to the QCM chip, the output end of the data acquisition circuit is connected to the computer, the QCM chip vibrates under the drive of the driving circuit to generate a stable vibration frequency, and the data acquisition circuit collects the vibration frequency of the QCM chip in real time. , and transmit the vibration frequency data to the computer for monitoring and storage, the microscopic observation device is located above the visible autoclave, and is used to observe the measured natural gas hydrate on the QCM chip.

Further, the kettle wall of the kettle body is provided with a water jacket, the water inlet of the water jacket is connected with the water outlet of the constant temperature tank, and the water outlet of the water jacket is connected with the water inlet of the constant temperature tank.

Further, the visible high pressure reaction kettle includes an upper cover, the upper cover is threadedly connected with the kettle body, and a circular viewing window is arranged above the upper cover.

Further, the kettle body is connected with a temperature transmitter and a pressure transmitter, the temperature transmitter is used to measure the temperature of the gas phase environment in the kettle body, and the pressure transmitter is used to measure the pressure of the gas phase environment in the kettle body.

The present invention also provides a method for testing using the above-mentioned real-time testing device for molecular adsorption mechanism on the surface of natural gas hydrate, comprising the following steps:

S1, clean the QCM chip with nitrogen and place it in the QCM probe;

S2, debug the drive circuit and the data acquisition circuit through the computer;

S3, use spray to form a thin water film on the QCM chip;

S4, open the constant temperature tank to transport the circulating medium into the kettle body, and adjust the temperature in the kettle body to the temperature required for the experiment;

S5, after observing that the water film on the QCM chip freezes through the microscopic observation device, adjust the natural gas cylinder to the experimental pressure, and slowly pass the natural gas into the kettle to form natural gas hydrate;

S6, depressurize or increase temperature, and observe the decomposition of natural gas hydrate through a microscopic observation device.

The test device provided by the invention can use the QCM chip and the QCM probe to test the vibration frequency change of the methane molecule and the water molecule on the surface of the natural gas hydrate in real time during the interaction, so as to realize the real-time monitoring of the surface adsorption mechanism from the formation to the decomposition process of the natural gas hydrate. Measurements include: real-time interaction between molecular layers by adsorption measurement, changes in hardness, thickness, water content and viscoelasticity. The current precision of QCM chips can monitor the vibration frequency changes of the adsorption mass on the surface of the chip in nanogram level in real time, thereby The observation of intermolecular adsorption on the surface can be easily realized; the test device provided by the present invention can rapidly reduce the temperature of the kettle body through a constant temperature bath.

Description of drawings

FIG. 1 is a schematic structural diagram of a real-time testing device for the molecular adsorption mechanism on the surface of natural gas hydrate according to the present invention.

FIG. 2 is a schematic structural diagram of a visual high-pressure reaction kettle of a real-time testing device for the molecular adsorption mechanism on the surface of natural gas hydrate according to the present invention.

In the picture: natural gas cylinder-1, constant temperature tank-2, computer-3, data acquisition circuit-4, drive circuit-5, microscopic observation equipment-6, visual autoclave-7, upper cover-71, kettle Body-72, Circular Window-73, QCM Probe-74, QCM Chip-75, First Level Valve-81, Second Level Valve-82, Third Level Valve-83, Temperature Transmitter-84, Pressure Variable Feeder-85, fourth pipeline-86, first pipeline-11, second pipeline-21, third pipeline-22.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the embodiments of the present invention will be further described below with reference to the accompanying drawings.

Please refer to FIG. 1 , an embodiment of the present invention provides a real-time testing device for the molecular adsorption mechanism on the surface of natural gas hydrate, including a natural gas cylinder 1, a constant temperature tank 2, a computer 3, a data acquisition circuit 4, a driving circuit 5, a microscopic observation Equipment 6, visual autoclave 7.

Natural gas is stored in the natural gas cylinder 1. The gas outlet of the natural gas cylinder 1 is communicated with the air inlet of the visible high pressure reactor 7 through the first pipeline 11. The first pipeline 11 is provided with a first horizontal valve 81 and a second horizontal valve 81. Valve 82 and third horizontal valve 83, the first horizontal valve 81 cooperates with the second horizontal valve 82 and the third horizontal valve 83 to adjust the pressure in the visible high pressure reactor 7, and the second horizontal valve 82 cooperates with the first horizontal valve 81 and the third horizontal valve 83. The three-level valve 83 discharges the gas in the visible autoclave 7 and the first pipeline 11 after the experiment ends.

The visible autoclave 7 includes a threaded upper cover 71 and a kettle body 72, a circular viewing window 73 is arranged on the upper part of the upper cover 71, and a QCM (Quartz Crystal Microbalance, Quartz Crystal Microbalance) probe 74 is set in the kettle body 72, a QCM probe A QCM chip 75 is placed in 74, the QCM chip 75 is connected to one end of the drive circuit 5 through a cable, the other end of the drive circuit 5 is connected to the computer 3 through a cable, and the receiving end of the data acquisition circuit 4 is connected to the QCM chip 75 through a cable. The output end of the circuit 4 is connected to the computer 3 through a cable. The QCM chip 75 vibrates under the drive of the drive circuit 5 to generate a stable vibration frequency. The data acquisition circuit 4 collects the vibration frequency of the QCM chip 75 in real time and transmits the vibration frequency data to the computer. 3. Monitor and store; QCM chip 75 selects QCM-D series chips from Sweden Bio-Olin Company, and drive circuit 5 and data acquisition circuit 4 are circuits corresponding to QCM chip 75 .

The kettle body 72 is provided with a temperature transmitter 84 and a pressure transmitter 85. The temperature transmitter 84 and the pressure transmitter 85 are connected to the kettle body 72 through a fourth pipeline 86, and the temperature transmitter 82 is used to measure the kettle body 72. The pressure transmitter 85 is used to measure the pressure of the gas-phase environment in the kettle body 72 according to the temperature of the gas-phase environment inside.

The kettle wall of the kettle body 72 is provided with a water jacket, the water inlet of the water jacket communicates with the water outlet of the constant temperature tank 2 through the second pipeline 21, and the water outlet of the water jacket communicates with the inlet of the constant temperature tank 2 through the third pipeline 22. The water port is connected, and the circulating medium is stored in the constant temperature tank 2. The circulating medium in the constant temperature tank 2 is transported to the water jacket through the second pipeline 21 to rapidly reduce the temperature of the kettle body 72. The circulating medium in the water jacket passes through the third pipe. The circuit 23 returns to the constant temperature tank 2. The constant temperature tank 2 has better cooling capacity, and its control accuracy can reach 0.1 degrees;

The microscopic observation device 6 is located above the circular viewing window 73, and can observe the measured gas hydrate on the QCM chip 75 from a better angle.

Embodiments of the present invention also provide a real-time testing method for molecular adsorption mechanism on the surface of natural gas hydrate, comprising the following steps:

Step S1, the QCM chip 75 is cleaned with nitrogen and placed in the QCM probe 74;

Step S2, debugging the drive circuit 5 and the data acquisition circuit 4 through the computer 3;

Step S3, a thin water film 76 is formed on the QCM chip 75 by spraying;

Step S4, cover the upper cover 71 and tighten it, open the constant temperature tank 2 to transport the ethylene glycol or silicone oil into the kettle body 72, and adjust the temperature in the kettle body 72 to the temperature required for the experiment (less than 0°C);

Step S5, after observing that the water film 76 on the QCM chip 75 freezes through the microscopic observation device 6, the natural gas cylinder 1 is adjusted to the experimental pressure (10MPa), and then the first horizontal valve 81 and the third horizontal valve 83 are opened. The natural gas is slowly introduced into the still body 72 to form natural gas hydrate;

Step S6, depressurize or raise the temperature, and observe the decomposition of natural gas hydrate through the microscopic observation device 6; the depressurization process is: the first horizontal valve 81, the second horizontal valve 82 and the third horizontal valve 83 are slowly opened when the first horizontal valve 81, the second horizontal valve 82 and the third horizontal valve 83 are closed. The second level valve 82 and the third level valve 83 discharge the natural gas in the kettle body 72 to reduce the gas pressure in the kettle body 72. The heating process is: heating the ethylene glycol or silicone oil in the thermostatic tank 2 to 90°C, and then The ethylene glycol or silicone oil is transported into the kettle body 72 to heat the kettle body 72 .

During the above-mentioned steps, the QCM chip 75 vibrates under the drive of the drive circuit 5 to generate a stable vibration frequency, and the data acquisition circuit 4 collects the vibration frequency of the QCM chip 75 in real time, and transmits the vibration frequency data to the computer 3 for monitoring and storage. , the vibration frequency data includes the real-time frequency records of the water film 76 from freezing to hydrate formation, and to hydrate decomposition. By analyzing the vibration frequency data, real-time surface adsorption data can be obtained, and then the surface adsorption mechanism can be developed. Research.

If the microscopic observation device 6 is tested with an ellipsometer, the thickness, refractive index, absorptivity, surface structure, surface process and surface reaction of the water film 76 can also be measured at the same time, and then corresponding analysis and research can be carried out.

In this document, the related terms such as front, rear, upper and lower are defined by the positions of the components in the drawings and the positions between the components, which are only for the clarity and convenience of expressing the technical solution. It should be understood that the use of the locative words should not limit the scope of protection claimed in this application.

The above-described embodiments and features of the embodiments herein may be combined with each other without conflict.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (4)

1. a real-time testing device for molecular adsorption mechanism on the surface of natural gas hydrate, is characterized in that, comprises natural gas cylinder, constant temperature tank, computer, data acquisition circuit, drive circuit, microscopic observation equipment and visible autoclave, described natural gas Natural gas is stored in the gas cylinder, and the gas outlet of the natural gas gas cylinder is communicated with the gas inlet of the visible high pressure reactor through a first pipeline, and a first horizontal valve, a second horizontal valve and a third horizontal valve are arranged on the first pipeline. Horizontal valve, the first horizontal valve cooperates with the second horizontal valve and the third horizontal valve to adjust the pressure in the visible autoclave, and the second horizontal valve cooperates with the first horizontal valve and the third horizontal valve to discharge after the experiment is over The visible high-pressure reaction kettle and the gas in the first pipeline can be seen. The visible high-pressure reaction kettle includes a kettle body, and the constant temperature tank is communicated with the kettle body, and a circulating medium is stored therein to reduce the temperature of the kettle body. A QCM probe is arranged in the kettle, a QCM chip is placed in the QCM probe, the QCM chip is connected with one end of the drive circuit, the other end of the drive circuit is connected with the computer, and the receiving end of the data acquisition circuit is connected with the QCM chip, The output end of the data acquisition circuit is connected to the computer, the QCM chip vibrates under the drive of the drive circuit to generate a stable vibration frequency, the data acquisition circuit collects the vibration frequency of the QCM chip in real time, and transmits the vibration frequency data to the computer. For monitoring and storage, the microscopic observation device is located above the visible autoclave and is used to observe the measured natural gas hydrate on the QCM chip; the kettle wall of the kettle body is provided with a water jacket, and the water jacket is The water inlet of the thermostatic tank is connected with the water outlet of the constant temperature tank, the water outlet of the water jacket is connected with the water inlet of the constant temperature tank, and the circulating medium is stored in the constant temperature tank, and the circulating medium is selected from ethylene glycol or silicone oil. 2. The device for real-time testing of molecular adsorption mechanism on natural gas hydrate surfaces according to claim 1, wherein the visible autoclave comprises an upper cover, the upper cover is threadedly connected to the kettle body, and the upper cover is threaded. Set a circular window above. 3. The real-time testing device of natural gas hydrate surface molecular adsorption mechanism according to claim 1, wherein the still body is connected with a temperature transmitter and a pressure transmitter, and the temperature transmitter is used to measure the The temperature of the gas phase environment, the pressure transmitter is used to measure the pressure of the gas phase environment in the kettle. 4. the method that utilizes the natural gas hydrate surface molecular adsorption mechanism real-time testing device to test according to claim 1, is characterized in that, comprises the following steps: S1, clean the QCM chip with nitrogen and place it in the QCM probe; S2, debug the drive circuit and the data acquisition circuit through the computer; S3, use spray to form a thin water film on the QCM chip; S4, open the constant temperature tank to transport the circulating medium into the kettle body, and adjust the temperature in the kettle body to the temperature required for the experiment; S5, after observing that the water film on the QCM chip freezes through the microscopic observation device, adjust the natural gas cylinder to the experimental pressure, and slowly pass the natural gas into the kettle to form natural gas hydrate; S6, depressurize or increase temperature, and observe the decomposition of natural gas hydrate through a microscopic observation device.

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